Back in December, we talked about an ingenious solution that entailed the combination of solar and hydrogen fuel for energy generation throughout the day/night cycle. Well this time around, a group of researchers at NextPV (a collaborative laboratory operated by French National Center for Scientific Research and the University of Tokyo) are developing a more ‘spacious’ solar solution prototype for clean energy generation throughout 24 hours. This scope encompasses flying solar balloons that could be deployed above the clouds (6 km or 3.7 miles above the ground). And from rough estimations, such airborne solar installations with special sensors can theoretically produce 3-times as much electricity (in sq ft basis) than their ground-based counterparts.

As since we are talking about the general sense of solar-based affairs, in practical terms there are major predicaments to conventional ground based solar panels. The first one obviously relates to its relatively high cost, which fortunately is dropping at a healthy rate for future customers. But the other two issues directly relate to the intrinsic weather pattern of earth – namely the periodical obstruction posed by clouds that can affect the energy output and the general inability of solar arrays to produce energy during the night. Suffice it to say, the solar balloon concept literally rises up to the challenge of traversing beyond the clouds to take advantage of the maximum exposure of sunlight – which can potentially translate to far greater efficiency.

As Jean-François Guillemoles, a CNRS senior researcher, made it clear –

The main problem with photovoltaic energy is that sunlight can be obscured by clouds, which makes electrical production intermittent and uncertain. But above the cloud cover, the sun shines all day, every day. Anywhere above the planet, there are very few clouds at an altitude of 6 km—and none at all at 20 km. At those heights, the light comes directly from the Sun, as there are no shadows and hardly any diffusion by the atmosphere. As the sky loses its blue color, direct illumination becomes more intense: the concentration of solar energy results in more effective conversion, and hence higher yields.

Credit: PixScience.fr/ Grégoire Cirade.

But the ambit is not as simple as just attaching photovoltaic panels to a weather balloon, and then sending it sky high. Rather the solar balloon is envisioned as more collective system that will also utilize hydrogen as the ‘energy vector’. In other words, the airborne solar power system will be endowed with the capacity to obtain hydrogen via electrolysis (from the ‘extra’ solar electricity produced during the day). This procured hydrogen in turn can be recombined with oxygen in a fuel cell for electricity generation during the night. Furthermore, some of the hydrogen can also be used to inflate the solar balloons and keep them aloft – thus alluding towards a self-sustaining mechanism.

Guillemoles further added –

A moored high-altitude balloon of reasonable size could store about 10 days equivalent of its own solar electricity production, which is more than enough to meet energy needs overnight, until production resumes in the morning. Reducing structural and installation costs, ensuring high conversion efficiency and providing nearly round-the-clock access to an abundant power supply would help prove that clean energy can cost less to produce than coal-fired electricity.

Of course in the present circumstance, the solar balloons are still in their conceptual stage. But the good news is, the researchers are working towards contriving a fully working prototype within just two years. Now whether this technological scope (with its paraphernalia tethers and cables) can compete with ground-based solar power costs in two years, is a question for yet another day. But one can’t deny the sheer potential of an airborne solar power system that will not only eschew the need for enormous ground coverage but also save money when it comes to manufacturing of hundred million tons of glass needed for conventional photovoltaic cells.